Method and apparatus for recovering energy from driving engines

ABSTRACT

Method for recovering energy from engines ( 20 ), characterized in that it comprises the following steps: operating the engine ( 20 ) by means of a pressurised fluid (A 1 ,A 2 ); recovering the operating fluid (A 1 ,A 2 ) of the engine ( 20 ); supplying the recovered pressurised fluid to at least one tank ( 120 ) containing water; pressuring the water in said tank ( 120 ) by means of said pressurised fluid; supplying said pressurised water to a turbine ( 140 ) operating a secondary shaft ( 2 ); recovering the outlet water from the turbine ( 140 ); supplying the outlet water from the turbine ( 140 ) to the said at least one tank ( 120 ) for pressurisation; repetition of the cycle.

The present invention relates to a method and an associated apparatusfor recovering energy from engines.

It is known that, in the various technical sectors where the operationof devices of various kinds is required, there is an increasinglyfrequent need to optimize the efficiency levels of the various enginesin order to reduce the costs associated with the consumption of energy,whatever the form used, (electricity, gas, oil), and in order to limitthe environmental impact and pollution of the surrounding environment.

It is also known that various efforts have been made in this connection,namely with the introduction of energy recovery apparatus into thevarious operating cycles, but without the effective energy gain achievedbeing such as to justify the use of said recovery apparatus on a largescale.

The technical problem which is posed, therefore, is that of providing anapparatus and a method for recovering energy from engines for devices ofvarious kinds, which results in an adequate and effective energy gain atthe end of the operating cycle.

In connection with this problem it is also required that this deviceshould have small dimensions, be easy and inexpensive to produce andassemble and be able to be easily installed at any user premises andalso in combination with already existing engines.

These results are achieved according to the present invention by amethod for recovering energy from engines according to thecharacteristic features of claim 1 and an apparatus for implementing themethod according to the characteristic features of claim 9.

Further details may be obtained from the following description of anon-limiting example of embodiment of the subject of the presentinvention provided with reference to the accompanying drawings in which:

FIG. 1 shows a schematic diagram of a first embodiment of the energyrecovery apparatus according to the present invention; and

FIG. 2 shows a schematic diagram of a second embodiment of the energyrecovery apparatus according to the present invention.

As shown in FIG. 1, an engine 20 operates a primary shaft 1, which inthe example according to the figure is rotating, but may be also beoperated displaceably. The engine 20 in the example shown consists of apneumatic engine comprising a pair of cylinders 21 which house movablyinside them a respective piston 22 moved by compressed air A1 suppliedby a primary energy source 10 comprising a compressor 11 and a tank 12.

By suitably determining the time lag between the two pistons 22 it ispossible to produce an alternating thrust/return movement thereof suchas to cause, in a conventional manner, operation of the primary shaft 1during the thrust phase and an action on the compressed air A2, presentinside each cylinder 21 after the thrust phase of the pistons 22, sothat said air A2 can be conveyed into a line 110 for supplying an energyrecovery apparatus 100 according to the present invention.

According to a preferred embodiment it is envisaged that a storage tank23 (shown in broken lines in the figure) is arranged between the line110 and the cylinders 21 of the engine 20, said tank being supplied bymeans of pipes 23 a connected to the respective cylinders 21.

In greater detail, said recovery apparatus 100 comprises at least onetank 120 (three in the example shown) containing water; each tank 120has an inlet 121 for the pressurised air supplied by the line 110, atleast one inlet 126 for the water and at least one, outlet 122 for thewater which is pressurised by the air supplied to the tank.

The pressurised air inlet 121 is regulated by a controlled interceptvalve 121 a.

Preferably an outlet valve 124 for the pressurised air contained insidethe tank 120 is also arranged in the region of the air inlet valve 121,said air being in turn also able to be recovered and, for example, beingstored in a tank 124 a for subsequent use, resulting in further energyrecovery.

The pressurised water from each tank 120 is supplied to a line 130 forsupplying a turbine 140 situated at a higher level than the tank 120 sothat, when there is no thrust due to the pressurised air A2, the waterhead is in equilibrium with the free surface being positioned in thevicinity of the inlet to the turbine 140.

It is envisaged, moreover, that the outlet of the tanks 120 is in turnregulated by a controlled valve 122 a.

During the operating cycle, the turbine 140 starts to move as a resultof the thrusting action of the pressurised water and in turn causesrotation of a secondary shaft 2 which may be used to operate auxiliarydevices of various kinds.

In the example shown it is envisaged that the shaft 2 operates an airpump 40 able to pump pressurised air either to the primary tank 12 ordirectly to the pneumatic engine 20 by means of a duct 41 which, asshown in broken lines, may also be connected to the inlet pipe 110 ofthe first tank 120.

In a bypassing arrangement or in parallel, the secondary shaft 2 mayalso operate an electric motor 50, the shaft 51 of which may beconnected to various user devices.

The turbine operating water, once all of its potential energy has beenused up, is discharged via pipes 141 either directly into the tank 120or, in a preferred embodiment as shown, into a tank 150 provided withoutlets 151 for the return of the water to the tank(s) 120.

In both cases the presence of a normally closed valve 125 situatedbetween the water return pipes and the tank 120 is envisaged, said valvebeing able to open the delivery for the time need to restore the levelof water inside the tank 120 itself.

It is envisaged, moreover, that all the sequences of the operating cycleof the apparatus and the primary engine, as well as the intercept andregulating valves, are controlled by an associated control unit 1000able to determine the sequences and actuation of valves andservomechanisms for controlling and operating the various auxiliaryparts of the apparatus, which parts, being conventional per se, are notdescribed in detail. In particular, the sequences and theopening/closing times of the valves 121 a, 122 a and 125 will besynchronized both with each other and with the cycle time of the pistons21 so that, during the thrust phase of the piston, the air inlet valve121 a is closed and the air discharge valve 124 and in sequence theinlet valve 125 for the water which could not enter with the tank stillunder pressure are opened.

As shown in FIG. 2 it is also envisaged being able to achieve furtherenergy recovery by means of an apparatus according to the invention witha dual stage. In this configuration it is envisaged duplicating therecovery apparatus 100 by connecting via a pipe 1110 the breather valve124 of the first stage to the inlet valve 121 a of the pipe 121supplying the compressed air to the first tank 120.

In this way the compressed air recovered from the first stage can beused to operate a second shaft 2 of a second turbine 140, operation ofwhich constitutes a total gain since it is obtained only by componentswith operation by means of recovery from the first stage.

It is envisaged moreover being able to increase further the number ofstages in cascade so as to obtain further energy recovery and that thereturn pipe 41 from the pump 40 may be connected by means of anextension 1041 to the pipe 1110 supplying the second stage 100.

According to the invention it is envisaged moreover providing a methodfor recovering energy from engines 20, comprising the following steps:

-   -   operating the engine 20 by means of a pressurised fluid A1,A2;    -   recovering the operating fluid A1,A2 of the engine 20;    -   supplying the recovered pressurised fluid to at least one tank        120 containing water;    -   pressurising the water in said tank 120 by means of said        recovered fluid;    -   supplying said pressurised water to a turbine 140 operating a        secondary shaft 2;    -   recovering the outlet water from the turbine 140;    -   supplying the recovered water from the turbine 140 to the said        at least one tank 120 for pressurisation;    -   repetition of the cycle.

It is envisaged moreover that:

-   -   the outlet water from the turbine 140 may be stored inside a        central tank 150 forming a buffer for supplying the water to the        pressurisation tank 120;    -   the secondary shaft 2 is used to operate auxiliary devices such        as a pump 40 able to re-pressurise the operating fluid to be        sent to the engine 20.

In the case of the pneumatic engine illustrated, the pump 40 is an airpump which sends compressed air either to the cylinders 21 or to thestorage tank 12 supplying them.

In addition to this it is envisaged that the secondary shaft 2 mayoperate an electric motor 50 bypassing or in parallel with the pump 40,in keeping with the values of the residual energy available.

It is therefore clear how operation of the secondary shaft 2 is obtainedby means of free recovery of energy resulting from the reuse of thepressurised operating fluid of the engine 20; consequently the energydelivered from the turbine 140 to the shaft 2 may be regarded as totalgain in the operating cycle.

Tests carried out on pneumatic engines, according to the exampleillustrated, i.e. engines which have a normal average efficiency ofaround 0.5 to 0.6%, have confirmed overall efficiency levels of theengine which are increased up to 0.8 to 0.9% in the condition where theengine forms a closed loop with the energy recovery apparatus 100according to the invention operating an air pump 40 according to thediagram shown.

With reference to FIG. 2 it is also envisaged being able to obtainfurther energy recovery by means of a method applied to an apparatusaccording to the invention with a dual stage.

In such a case it is envisaged duplicating the recovery apparatus 100 byconnecting via a pipe 1110 the breather valve 124 of the first stage tothe inlet valve 121 a of the pipe 121 for supplying the compressed airto the first tank 120.

Consequently the method comprises a further step consisting in:

-   -   recovery of compressed air from the first tank 120 of the first        stage and supplying thereof to the first tank of the second        stage;    -   repetition of the basic cycle so as to operate a second shaft 2        of a second turbine 140, operation of which represents a total        gain since it is obtained only by components with operation by        means of recovery from the first stage, which allows a        considerable increase in the overall efficiency of the        apparatus.

Further energy recovery is possible by means of a pipe leading from thepump 40 and extended with the section 1041 to the inlet of the firsttank of the second stage.

Although illustrated in relation to a pneumatic engine, it is alsowithin the scope of the person skilled in the art to use the energyrecovery apparatus according to the present invention also incombination with different engines operating with pressurised fluidwhich may be recovered in order to pressurise the water in the tanks andcause operation of the turbine 140 of the secondary shaft 2.

Although the invention has been described in the context of a number ofembodiments and a number of preferred examples, the persons skilled inthe art will understand that the present invention also extends beyondthe embodiments described in a specific manner, according to the scopeof protection determined by the claims which follow.

1. Method for recovering energy from engines (20), characterized in thatit comprises the following steps: operating the engine (20) by means ofa pressurised fluid (A1,A2); recovering the operating fluid (A1,A2) ofthe engine (20); supplying the recovered pressurised fluid to at leastone tank (120) containing water; pressuring the water in said tank (120)by means of said pressurised fluid; supplying said pressurised water toa turbine (140) operating a secondary shaft (2); recovering the outletwater from the turbine (140); supplying the outlet water from theturbine (140) to the said at least one tank (120) for pressurisation;repetition of the cycle.
 2. Method according to claim 1, characterizedin that the step for recovering and supplying the pressurised fluid(A1;A2) of the engine (20) is performed by the same means (21, 22) foroperating the primary shaft (1) of the engine.
 3. Method according toclaim 1, characterized in that it envisages a step for storing theoutlet water from the turbine (140) inside a tank (150) before supplyingthereof to the at least one water pressurisation tank (120).
 4. Methodaccording to claim 1, characterized in that it envisages a stepinvolving operation by the secondary shaft (2) of a pump (40) able topressurise the operating fluid of the engine (20).
 5. Method accordingto claim 4, characterized in that the secondary shaft (2) operates anauxiliary electric motor (50) bypassing or in parallel with the pump(40).
 6. Method according to claim 1, characterized in that the engine(20) is a pneumatic engine operating a primary shaft (1).
 7. Methodaccording to claim 6, characterized in that the pneumatic engine (20) isoperated by a compressor (11).
 8. Method according to claim 4,characterized in that supplying of the pneumatic engine (20) isperformed via a storage tank (12) arranged between the compressor (11)and the engine itself.
 9. Method according to claim 1, characterized inthat the recovery cycle is a multi-stage cycle.
 10. Method according toclaim 9, characterized in that it comprises a step (124, 1110) forrecovering the pressurised fluid from the at least one tank (120) of afirst stage and supplying said recovered fluid to at least one secondtank (120) of at least one second stage (100) connected to a secondturbine (140).
 11. Method according to claim 4, characterized in thatsaid pump (40) has an outlet pipe (41) connected to the inlet of thefirst tank (120) of the first stage.
 12. Method according to claim 4,characterized in that said pump (40) has an outlet pipe (41) connectedto the inlet of the second tank (1041) of the second stage. 13.Apparatus for recovering energy from an engine (20) operated by apressurised fluid (A1,A2), characterized in that it comprises means(110) for recovering and supplying the operating fluid of the engine toat least one tank (120) containing water for pressurisation thereof,means (130) for supplying the pressurised water in said tank (120) to aturbine (140) operating a secondary shaft (2), means (141) forcollecting and supplying the outlet water from the turbine (140) to saidat least one tank (120) containing the water to be pressurised. 14.Apparatus according to claim 13, characterized in that said operatingmeans of the engine consist of at least one piston (22) movable insidean associated cylinder (21).
 15. Apparatus according to claim 14,characterized in that said operating means of the engine consist of atleast one pair of pistons (22) movable inside an associated cylinder(21).
 16. Apparatus according to claim 15, characterized in theoperating means (21, 22) of the engine (20) are time-lagged and able toperform recovery of the pressurised operating fluid (A1;A2) of the saidengine (20).
 17. Apparatus according to claim 11, characterized in thatsaid means (110) for recovering and supplying the operating fluid of theengine (20) consist of a line connecting together the at least one tank(120) and the operating means (21; 22) of the engine (20).
 18. Apparatusaccording to claim 17, characterized in that a tank (23) supplied viapipes (23 a) connected to the respective means (21) is arranged betweenthe line (110) and the operating means (21;22) of the engine (20). 19.Apparatus according to claim 13, characterized in that said at least onetank (120) for pressurising the water has at least one inlet (121)connected to the line (110) supplying the pressurised fluid, at leastone inlet (126) and at least one outlet (122) for delivering thepressurised water.
 20. Apparatus according to claim 19, characterized inthat said water and fluid inlets and outlet (122) are regulated byrespective control valves (121 a;125;122 a).
 21. Apparatus according toclaim 13, characterized in that said inlet valve (125) of the water tankis normally closed and able to regulate the filling level of the tank insynchronism with the operating means of the engine (20).
 22. Apparatusaccording to claim 13, characterized in that said valve (121 a)supplying the pressurised fluid is normally closed and opened incounter-synchronism with the water supply and water delivery valves(125).
 23. Apparatus according to claim 12, characterized in that saidmeans (130) for supplying the pressurised water to the turbine (140)consist of a line connected to said outlet (122) of the at least onepressurised water tank.
 24. Apparatus according to claim 13,characterized in that said water pressurisation tank (120) comprises acontrolled breather valve (124) for the pressurised air.
 25. Apparatusaccording to claim 13, characterized in the said means (141) forcollecting and supplying the turbine outlet water consist of directlines connected to the at least one tank (120).
 26. Apparatus accordingto claim 13, characterized in that it comprises a tank (150) for storingthe outlet water from the turbine (140), connected to said at least onewater pressurisation tank (120).
 27. Apparatus according to claim 13,characterized in that it comprises a pump (40) operated by the turbine(140) and able to pressurise the fluid to be sent to the engine (20).28. Apparatus according to claim 13, characterized in that the shaft (2)of the turbine (140) operates an auxiliary electric motor (50) bypassingor in parallel with the pump (40).
 29. Apparatus according to claim 13,characterized in the engine (20) is a pneumatic engine operating aprimary shaft (1).
 30. Apparatus according to claim 29, characterizedthat the pneumatic engine (20) is operated by a compressor (11). 31.Apparatus according to claim 29, characterized in the supplying of thepneumatic engine (20) is performed via a storage tank (12) arrangedbetween the compressor (11) and the engine itself.
 32. Apparatusaccording to claim 13, characterized in that it is a dual-stageapparatus (100).
 33. Apparatus according to claim 32, characterized inthat it comprises a pipe (1110) connecting together the first tank (120)of the first stage (100) and the first tank (120) of at least one secondstage (100).
 34. Apparatus according to claim 33, characterized in thesaid pipe (1110) is arranged between the breather valve (124) of thefirst tank (120) of the first stage (100) and the inlet valve (121 a) ofthe first tank (120) of the second stage (100).
 35. Apparatus accordingto claim 32, characterized in the said pump (40) has an outlet pipe (41)connected to the inlet of the first tank (120) of the first stage. 36.Apparatus according to claim 32, characterized in said pump (40) has anoutlet pipe (41) connected to the inlet of the second tank (1041) of thesecond stage.
 37. Apparatus according to claim 13, characterized in thatit comprises a control unit (1000) able to determine the sequences andactuation of valves and servo-mechanisms for controlling and operatingthe various auxiliary parts of the apparatus.